Her hair once again soaked in stale cave water, Kethra angrily flips her white locks dramatically to look up from punching the tar out of a shark.

In the torchlight, Kethra "the Blacksmith" Stormwind looks like a strange spectacle for the reavers to see: a short human girl with long white hair, one hand clenched from pummeling a shark and her other hand wielding the weapon of the mercenary group's leader aboveground.

"Your knight is dead and I clearly hold the weapon of Jolliver Grimjaw. Do you really want to keep fighting...like animals?" She rolls her eyes if suddenly remembering something then strikes the shark beside her another time.

Maul to-hit: 16 Damage: 8

 (And probably misses, splashing only a bit of water.)

"So? What's it gonna be?!" With a soft sigh, the wereboar's maul suddenly takes to the air and spins in front of Kethra as if she was just spinning a quarterstaff, (bonus action not very Patient Defense).

Kethra seems to think this is a pool party.

Davian heals Kethra again, for 11 hit points.

The fathomer tries to coil itself around Rubin again, despite him not being fully visible.

Attack: 18 Damage: 5 bludgeoning, grappled and restrained on hit

Forgot disadvantage for invisibility: 24

It somehow still manages to constrict around Rubin, hampering his movement greatly.

Jairus fires two crossbow bolts into the shark.

Attack: 21 Damage: 5 SA: 5

Attack: 13 Damage: 2

Both find their mark.

The shark tries to bite at Rubin again, this time taking advantage of his hampered movement.

Attack: 20 Damage: 18

He rips Rubin's armor to shreds and digs his teeth deeply into his stomach.

Slight retconning from last turn, Davian will actually wild shape into a giant octopus and attempt to grab the shark.

Attack: 10 Damage: 9, and grappled and restrained

And unfortunately for Rubin, misses.

Two of the reavers pull themselves into the boat, and stab at Kethra and Jairus.

Vs Kethra: 20 Damage: 6

Vs Jairus: 18 Damage: 7

The other two will both try to filet octo-Davian.

Attack: 9 Damage: 9

Attack: 19 Damage: 10

(Everyone is up.)

(I'll shoehorn our two new adventurers in when this encounter finishes, if I didn't say that already.)

Tyde will cast Acid Splash at the 2 reavers in the boat.

DEX save vs. DC 14 or each takes 2 acid damage.

Rubin attempts to escape the grapple...

Acrobatics: 13

Rubin escapes the grapple.

(Don't have time to roll the con saves now, but here's the disadvantage against Kethra: 14

as his bonus action Rubin casts Hunter's Mark on the thing that grabbed him, or the shark if he cannot see the thing that grabbed him.

Rubin can see the watery snake, yes.

Dex saves: 15, 16

Kethra will recklessly attempt to strike at the least injured of the boat reavers, following up with a swift series of kicks to the head.

Attack: 9 Damage: 11

Unarmed 1: 18 Damage: 8

Unarmed 2: 16 Damage: 8

She manages to take down both boat reavers in one go.

Octo-Davian tries to grab one of the reavers on him with his tentacles.

Attack: 8 Damage: 9 and restrained

He succeeds, pulling it close to him.

Jairus takes the opportunity to unleash a barrage of bolts on the vulnerable reaver.

Attack: 25 Damage: 5 SA: 1

Attack: 10 (Advantage if rest. reaver is still alive: 26) Damage: 6

Jairus downs the restrained bandit, and puts a bolt in the other one.

The remaining reaver frantically lashes out at the massive octopus next to him.

Attack: 17 Damage: 13

And misses due to his panic.

The fathomer tries to coil around Rubin again.

Attack: 15 Damage: 10 and restrained

(What are these disadvantage rolls?)

(Everyone is up.  One slightly injured (6 damage) reaver remains, as well as the fathomer.)

(In the future I think I'm going to include a spoiler with how much damage each enemy combatant has taken, both for my benefit and yours.)

Tyde will cast Fire Bolt at the fathomer.

Attack: 14 Damage: 4 fire damage.

Tyde lands a hit, but unsurprisingly fire doesn't seem terribly effective on a thing made out of water swimming in a lake.

(Rubin is up)

Rubin decides to take two shots at the watery snake...

Attack: 9 Damage: 14 (includes hunter's mark.)

Bonus Attack: 22 Damage: 7 (includes hunter's mark.)

Rubin lands two solid shots on the odd snake, but his bolts seem to not have quite the impact he would have expected (16 total damage to the snake this turn including Tyde's).

Kethra leans forward out of the boat to smack at the snake as well.

Attack: 9 Damage: 7

Unarmed: 14 Damage: 6

9 more damage.

Jairus also leans forward, this time striking with Reszur.

Attack: 14 Damage: 8 SA: 5

Octo-Davian lashes out with its tentacles at the one remaining reaver.

Attack: 10 Damage: 8 and restrained

But misses.

The reaver attempts to swim away, provoking an AoO from Davian:

Attack: 8 Damage: 10 and restrained

The fathomer tightens its hold on Rubin.

Attack: 16 Damage: 11

The reaver is caught trying to escape, and decides to swing anyways.

Attack: 5 Damage: 11

(16 total damage on the reaver.  Both the fathomer and the reaver are looking pretty bad.)

(Everyone is up)

(41 total damage on the Fathomer)

Rubin attacks the snake-thing once again...  (Includes hunter's mark damage.)

Attack: 10 Damage: 11

Bonus Attack: 27 Damage: 21

Tyde will cast Acid Splash on the fathomer (if the reaver is within 5 feet it can also get him?).

DEX save vs. DC 14 or take 4 acid damage.

Rubin lands two more accurate shots on the fathomer, but they're both somewhat weak.

Dex save: 20

Tyde's acid finally manages to eat through the snake, and it transforms back into a fat blue man before sinking into the sea.

Davian hugs the reaver once more.

Attack: 23 Damage: 7

And it squishes into pieces.

(Combat is over.)

You seem to hear two muffled voices calling for help from somewhere around the landing.